Whenever I click "Backup now" in the Backup GUI, the smaller "Back Up" window opends, and after a while I get the following error message:

Traceback (most recent call last):
  File "/usr/bin/duplicity", line 1359, in 
    with_tempdir(main)
  File "/usr/bin/duplicity", line 1342, in with_tempdir
    fn()
  File "/usr/bin/duplicity", line 1202, in main
    action = commandline.ProcessCommandLine(sys.argv[1:])
  File "/usr/lib/python2.7/dist-packages/duplicity/commandline.py", line 942, in ProcessCommandLine
    globals.backend = backend.get_backend(args[0])
  File "/usr/lib/python2.7/dist-packages/duplicity/backend.py", line 156, in get_backend
    return _backends[pu.scheme](pu)
  File "/usr/lib/python2.7/dist-packages/duplicity/backends/cloudfilesbackend.py", line 70, in __init__
    self.container = conn.create_container(container)
  File "/usr/lib/python2.7/dist-packages/cloudfiles/connection.py", line 250, in create_container
    response = self.make_request('PUT', [container_name])
  File "/usr/lib/python2.7/dist-packages/cloudfiles/connection.py", line 189, in make_request
    response = retry_request()
  File "/usr/lib/python2.7/dist-packages/cloudfiles/connection.py", line 182, in retry_request
    self.connection.request(method, path, data, headers)
  File "/usr/lib/python2.7/httplib.py", line 955, in request
    self._send_request(method, url, body, headers)
  File "/usr/lib/python2.7/httplib.py", line 989, in _send_request
    self.endheaders(body)
  File "/usr/lib/python2.7/httplib.py", line 951, in endheaders
    self._send_output(message_body)
  File "/usr/lib/python2.7/httplib.py", line 811, in _send_output
    self.send(msg)
  File "/usr/lib/python2.7/httplib.py", line 773, in send
    self.connect()
  File "/usr/lib/python2.7/httplib.py", line 1154, in connect
    self.timeout, self.source_address)
  File "/usr/lib/python2.7/socket.py", line 571, in create_connection
    raise err
error: [Errno 101] Network is unreachable

I use Rackspace CloudFiles as a storage backend, last backup was 3 days ago (successful. I have not changed any settings since then.